[Freeipa-devel] [PATCH 0049] Add support for protected tokens
Nathaniel McCallum
npmccallum at redhat.com
Wed May 28 20:44:25 UTC 2014
On Mon, 2014-05-26 at 16:57 +0200, Jan Cholasta wrote:
> On 13.5.2014 19:12, Nathaniel McCallum wrote:
> > On Tue, 2014-05-13 at 16:33 +0200, Jan Cholasta wrote:
> >> On 12.5.2014 21:02, Nathaniel McCallum wrote:
> >>> On Thu, 2014-05-08 at 13:51 -0400, Simo Sorce wrote:
> >>>> On Thu, 2014-05-08 at 12:26 -0400, Nathaniel McCallum wrote:
> >>>>> On Wed, 2014-05-07 at 11:17 -0400, Simo Sorce wrote:
> >>>>>> On Wed, 2014-05-07 at 09:54 -0400, Dmitri Pal wrote:
> >>>>>>> On 05/07/2014 09:05 AM, Nathaniel McCallum wrote:
> >>>>>>>> On Wed, 2014-05-07 at 11:42 +0200, Jan Cholasta wrote:
> >>>>>>>>> Hi,
> >>>>>>>>>
> >>>>>>>>> On 6.5.2014 17:08, Nathaniel McCallum wrote:
> >>>>>>>>>> On Tue, 2014-05-06 at 09:49 -0400, Nathaniel McCallum wrote:
> >>>>>>>>>>> On Mon, 2014-05-05 at 12:42 -0400, Nathaniel McCallum wrote:
> >>>>>>>>>>>> This also constitutes a rethinking of the token ACIs after the
> >>>>>>>>>>>> introduction of SELFDN support.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Admins, as before, have full access to all token permissions.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Normal users have read/search/compare access to all of the non-secret
> >>>>>>>>>>>> data for tokens assigned to them, whether protected or non-protected.
> >>>>>>>>>>>> Users can add or delete non-protected tokens and modify most of their
> >>>>>>>>>>>> metadata. However they cannot create, delete or modify protected tokens.
> >>>>>>>>>>>> Regardless of whether the token is protected or not, users cannot change
> >>>>>>>>>>>> a token's ownership or unique identity.
> >>>>>>>>>>>>
> >>>>>>>>>>>> In contrast, admins can create protected tokens. This protects the token
> >>>>>>>>>>>> from deletion or modification when assigned to users. Additionally, when
> >>>>>>>>>>>> a user account is deleted, the assigned non-protected tokens are deleted
> >>>>>>>>>>>> but the protected tokens are merely orphaned. This permits the token to
> >>>>>>>>>>>> be reassigned without having to recreate it. This last point is
> >>>>>>>>>>>> particularly useful in the case of hardware tokens.
> >>>>>>>>>>>>
> >>>>>>>>>>>> https://fedorahosted.org/freeipa/ticket/4228
> >>>>>>>>>>>>
> >>>>>>>>>>>> NOTE: This patch depends on my patch 0048.
> >>>>>>>>>>> This new version makes ipatokenDisabled visible for token owners. It is
> >>>>>>>>>>> also writable if the token is non-protected. This additionally fixes:
> >>>>>>>>>>>
> >>>>>>>>>>> https://fedorahosted.org/freeipa/ticket/4259
> >>>>>>>>>> This new version changes the way the default value of protected is setup
> >>>>>>>>>> in accordance with the changes made for the review of my patch 0048.2.
> >>>>>>>>>>
> >>>>>>>>>> Nathaniel
> >>>>>>>>> Is using the ipatokenprotected attribute the final design?
> >>>>>>>> No. Alternate designs are welcome. The code is easy enough to modify.
> >>>>>>>>
> >>>>>>>>> I did not dig too deep into this, but I think it might be better to
> >>>>>>>>> instead use the managedby attribute on a token to limit who can delete
> >>>>>>>>> (or administer in other way) the token. On otptoken-add, managedby would
> >>>>>>>>> be set to the "whoami" user DN, unless run with --protected, in which
> >>>>>>>>> case managedby would be left empty. Then, when deleting a user, the
> >>>>>>>>> token would be deleted only if the user manages the token.
> >>>>>>>> It seems to me that the mechanics of this are roughly the same as
> >>>>>>>> protected, just with a different syntax. The cost of this is more
> >>>>>>>> complex ACIs. In particular, we'd have to use two userdn clauses (is
> >>>>>>>> this possible?) instead of a simple filter. If there is a clear benefit,
> >>>>>>>> we can justify the more obtuse syntax.
> >>>>>>>
> >>>>>>> We usually try not to create new attributes until it is fully justified.
> >>>>>>> I would like Simo to chime in on this.
> >>>>>>
> >>>>>> I would also prefer to reuse existing attributes and mechanism if
> >>>>>> possible and if it will not preclude future work.
> >>>>>>
> >>>>>> In this case, it "sounds" like managed-by has the appropriate meaning:
> >>>>>> "who manages the token ?" -> myself, admin, other, none ?
> >>>>>>
> >>>>>> Nathaniel can you send 2 lines showing the difference in ACIs between
> >>>>>> using managed-by vs a new attribute ?
> >>>>>
> >>>>> These are the ACIs using the protected mechanism:
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >>>>> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >>>>> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >>>>> || ipatokenSerial || ipatokenOwner || ipatokenProtected")(version 3.0;
> >>>>> acl "Users can read basic token info"; allow (read, search, compare)
> >>>>> userattr = "ipatokenOwner#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipatokenTOTP)")(targetattrs =
> >>>>> "ipatokenOTPalgorithm || ipatokenOTPdigits ||
> >>>>> ipatokenTOTPtimeStep")(version 3.0; acl "Users can see TOTP details";
> >>>>> allow (read, search, compare) userattr = "ipatokenOwner#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipatokenHOTP)")(targetattrs =
> >>>>> "ipatokenOTPalgorithm || ipatokenOTPdigits")(version 3.0; acl "Users can
> >>>>> see HOTP details"; allow (read, search, compare) userattr =
> >>>>> "ipatokenOwner#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter =
> >>>>> "(&(objectClass=ipaToken)(!(ipatokenProtected=TRUE)))")(targetattrs =
> >>>>> "description || ipatokenDisabled || ipatokenNotBefore ||
> >>>>> ipatokenNotAfter || ipatokenVendor || ipatokenModel ||
> >>>>> ipatokenSerial")(version 3.0; acl "Users can write basic token info";
> >>>>> allow (write) userattr = "ipatokenOwner#USERDN";)
> >>>>>
> >>>>> aci: (target = "ldap:///ipatokenuniqueid=*,cn=otp,$SUFFIX")(targetfilter
> >>>>> = "(&(objectClass=ipaToken)(!(ipatokenProtected=TRUE))))")(version 3.0;
> >>>>> acl "Users can create and delete tokens"; allow (add, delete) userattr =
> >>>>> "ipatokenOwner#SELFDN";)
> >>>>>
> >>>>> This is what they look like using managedBy (I have not tested this):
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >>>>> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >>>>> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >>>>> || ipatokenSerial || ipatokenOwner || ipatokenProtected")(version 3.0;
> >>>>> acl "Users can read basic token info"; allow (read, search, compare)
> >>>>> userattr = "ipatokenOwner#USERDN"; allow (read, search, compare)
> >>>>> userattr = "managedBy#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipatokenTOTP)")(targetattrs =
> >>>>> "ipatokenOTPalgorithm || ipatokenOTPdigits ||
> >>>>> ipatokenTOTPtimeStep")(version 3.0; acl "Users can see TOTP details";
> >>>>> allow (read, search, compare) userattr = "ipatokenOwner#USERDN"; allow
> >>>>> (read, search, compare) userattr = "managedBy#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipatokenHOTP)")(targetattrs =
> >>>>> "ipatokenOTPalgorithm || ipatokenOTPdigits")(version 3.0; acl "Users can
> >>>>> see HOTP details"; allow (read, search, compare) userattr =
> >>>>> "ipatokenOwner#USERDN"; allow (read, search, compare) userattr =
> >>>>> "managedBy#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >>>>> "description || ipatokenDisabled || ipatokenNotBefore ||
> >>>>> ipatokenNotAfter || ipatokenVendor || ipatokenModel ||
> >>>>> ipatokenSerial")(version 3.0; acl "Managers can write basic token info";
> >>>>> allow (write) userattr = "managedBy#USERDN";)
> >>>>>
> >>>>> aci: (targetfilter = "(objectClass=ipaToken)")(version 3.0; acl
> >>>>> "Managers can delete tokens"; allow (delete) userattr =
> >>>>> "managedBy#USERDN";)
> >>>>>
> >>>>> aci: (target = "ldap:///ipatokenuniqueid=*,cn=otp,$SUFFIX")(targetfilter
> >>>>> = "(objectClass=ipaToken)")(version 3.0; acl "Users can create
> >>>>> self-managed tokens"; allow (add) userattr = "ipatokenOwner#SELFDN" and
> >>>>> userattr = "managedBy#SELFDN";)
> >>>>>
> >>>>> In short:
> >>>>> 1. Owner and manager get read, search and compare.
> >>>>> 2. Manager gets write (to select attributes) and delete.
> >>>>> 3. Users can create self-managed tokens for themselves only.
> >>>>>
> >>>>> The otptoken-add command should gain the following defaults:
> >>>>> 1. The owner defaults to the user adding the token.
> >>>>> 2. If owner == user adding token, managedBy defaults to owner.
> >>>>> 3. Otherwise, managedBy defaults to None.
> >>>>>
> >>>>> This means that if neither owner nor managedBy are specified, the
> >>>>> default is a self-owned, self-managed token. Likewise, if a different
> >>>>> owner is specified, no manager is assumed.
> >>>>>
> >>>>> rcrit expresses worry that ipalib's ACI parser may not handle the above
> >>>>> syntax. This will become clear during testing if we want this approach.
> >>>>>
> >>>>> Does this look sane?
> >>>>
> >>>> I am not entirely sure your ACI syntax is always right for the second
> >>>> set. and perhaps we want to duplicate ACIs in some cases (once for owner
> >>>> once for manager).
> >>>>
> >>>> I think the read ACIs do not need to list managedby ? Do we plan to have
> >>>> a manager that is another regular user but not the owner nor an admin ?
> >>>>
> >>>> In any case I prefer the sytnax that uses managedby, as it has more
> >>>> potential.
> >>>
> >>> Attached is a new version of the patch which implements the feature
> >>> using managedBy instead of ipatokenProtected. One important thing needs
> >>> to be said about this patch. I am not exposing managedBy in either the
> >>> UI, the CLI or LDAP (ACI). Do we care about this? If yes, should I
> >>> expose this similar to owner or as a relationship?
> >>
> >> I would expose it, as a relationship. (Note that ipatokenowner should
> >> ideally be represented as a relationship too, but the framework does not
> >> support 1-to-many relationships ATM.)
> >
> > So since this is a 1-to-many relationship we shouldn't expose it?
> >
> > Or should I do it like owner is currently done?
>
> Do it like managedby is done in the host plugin (see
> "attribute_members", "relationships", etc.)
>
> >
> >>
> >> Just curious, why are the ACIs divided like this:
> >>
> >> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >> || ipatokenSerial || ipatokenOwner")(version 3.0; acl "Users/managers
> >> can read basic token info"; allow (read, search, compare) userattr =
> >> "ipatokenOwner#USERDN" or userattr = "managedBy#USERDN";)
> >> aci: (targetfilter = "(objectClass=ipatokenTOTP)")(targetattrs =
> >> "ipatokenOTPalgorithm || ipatokenOTPdigits ||
> >> ipatokenTOTPtimeStep")(version 3.0; acl "Users/managers can see TOTP
> >> details"; allow (read, search, compare) userattr =
> >> "ipatokenOwner#USERDN" or userattr = "managedBy#USERDN";)
> >> aci: (targetfilter = "(objectClass=ipatokenHOTP)")(targetattrs =
> >> "ipatokenOTPalgorithm || ipatokenOTPdigits")(version 3.0; acl
> >> "Users/managers can see HOTP details"; allow (read, search, compare)
> >> userattr = "ipatokenOwner#USERDN" or userattr = "managedBy#USERDN";)
> >>
> >> IMHO you could make them less complex by dividing them like this:
> >>
> >> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >> || ipatokenSerial || ipatokenOwner || ipatokenOTPalgorithm ||
> >> ipatokenOTPdigits || ipatokenTOTPtimeStep")(version 3.0; acl "Owner can
> >> read token details"; allow (read, search, compare) userattr =
> >> "ipatokenOwner#USERDN";)
> >> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >> || ipatokenSerial || ipatokenOwner || ipatokenOTPalgorithm ||
> >> ipatokenOTPdigits || ipatokenTOTPtimeStep")(version 3.0; acl "Managers
> >> can read token details"; allow (read, search, compare) userattr =
> >> "managedBy#USERDN";)
> >
> > The first set is organized by objectClass. The second by userattr. I
> > have no strong opinion on this matter, though performance is probably a
> > consideration. Do any DS guys want to chime in?
>
> I would still like to know someone else's opinion on this, but if
> there's none, let's keep it your way.
>
> >
> >> Would it make sense to keep --protected as a flag in otptoken-add as a
> >> shortcut for "entry_attrs['managedby'] = None"?
> >
> > I can't think of a use case for this. The only use case I *can* think of
> > is an admin creating a non-protected token for a user.
>
> OK.
>
> >
> >> Would it make sense to default managedby to the current bind DN in
> >> otptoken-add, even if it's not a user DN? (Do we want to allow running
> >> otptoken-add by hosts/services/other non-users?)
> >
> > No idea. Dmitri?
>
> We can add this later if necessary.
>
> >
> >> Is orphaning a token when a user is deleted only if it is not managed by
> >> any other users the intended behavior? It just seems sort of strange to
> >> me, since it changes the token from unprotected to protected.
> >
> > I don't think that is the behavior. We orphan the token if the owner is
> > not listed as a manager. If the owner is listed as a manager, we delete
> > the token.
> >
> > Put another way, protected tokens are orphaned and unprotected tokens
> > are deleted.
> >
> > If I didn't implement that, please point out my bug.
>
> Sorry, my bad, your code is right. You can make it simpler, though:
>
> orphan = [x for x in token.get('managedby', []) if x == dn]
>
> (The "len() == 0" check is not necessary and using list comprehensions
> makes the code more readable than using filter.)
The attached version fixes all the above issues. Two issues that may
remain:
1. There is no option to set managedBy during otptoken-add or
otptoken-mod. This is probably okay.
2. I can't figure out how to get the framework to actually show
managedBy in command output (like otptoken-show). This means you can
add/remove relationships using otptoken-add-managedby and
otptoken-remove-managedby, but you can't actually see the list of
managers. What am I missing?
Also, it would be helpful if someone with DS expertise could answer the
question about the performance of the ACI structure options as listed
above.
Nathaniel
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